The present invention relates to a process and system for the operation of a resistive moisture sensor.
Resistive moisture sensors are used for instance in order to report moisture or raindrops on the windshield of a motor vehicle so as to control the windshield wiper automatically or semiautomatically. For this purpose, conductive paths are applied to the windshield or to some other suitable place so that the resistance between the conductive paths decreases with the amount of moisture present.
For evaluating this change in resistance, resistance measuring circuits have become known in which finally the voltage on the moisture sensor upon the presence of a predetermined current is measured.
In that case, there is an inversely proportional dependence between the voltage and the amount of moisture; in other words, for instance, a first drop to fall on a dry windshield produces a relatively large change in voltage while, if the windshield is already wet, a further drop results in only a smaller change.